High demands are made on a cartridge for a sanitary fitting. It has to remain sealed over a long period of time. It is to be easy to actuate and in the same valve position is, as far as possible, always to deliver water at the same temperature. It has to be able to be produced efficiently and inexpensively, and the number of parts that are subject to wear is to be as low as possible.
The components of a cartridge under strain as a result of wear are the control lever and the components that are connected to and actuated by it, such as the bushing in which it is mounted, and also the control disc that is connected to the cover disc.
In the case of vertical actuation of the actuating lever of the fitting that is connected to the control lever, the inflows are opened or closed; in the case of swiveling in the horizontal direction, the hot-water flow and the cold-water flow are mixed together. When the hot-water flow and the cold-water flow are mixed, the bushing in which the control lever is mounted and to which the control disc is secured by way of the cover disc is rotated in the housing of the cartridge enclosing it.
The bushing as a bearing of the control lever rests against the front wall of the cylindrically shaped cartridge. In accordance with the prior art, as is known, for example, from DE 102004056568 A1, the bushing can have two locating faces on the housing arranged at right angles to each other. The cover disc rests with its side that is remote from the control disc against the front wall of the housing of the cylindrically shaped cartridge and as a result has a horizontal locating face. Since the control lever is arranged outside the housing of the cartridge, the bushing penetrates the housing. The housing as a rule at this point has a vertical extension that encloses the bushing. As a result, the bushing can also have a vertical locating face there on the housing.
The housing of the cartridge has a predetermined height of installation. This is attained when assembling the cartridge, when connecting the housing to the base plate. So that the sealing elements between the individual components can be effective, the housing must be under a certain pre-stress in the axial direction. On account of tolerances and varying flexibility of the sealing elements, these forces can be of differing size for the individual cartridges.
When the control lever is actuated in order to open and close the inlets and outlets, the bushing and, conditional upon this, also the extension of the housing and its front wall are subjected to bending strain. When the cold-water flow and hot-water flow are mixed, as a result of rotating the bushing frictional forces develop in directions that are perpendicular to each other between the bushing and the front wall of the housing and also in the extension of the housing. In particular when the control lever is not mounted in a vertical extension of the housing, play can develop in the horizontal plane with respect to the front wall of the housing. Since the mixing and opening movements of the control lever occur simultaneously as a rule, tensile forces and pressure forces develop at right angles to each other in the housing.
All of these loads can, in a manner conditional on tolerances and play between the individual components, lead to hystereses in the mixing positions and in the position of the control disc during the opening and closing movements. As a result, reproduction of a certain water flow with a certain mixing temperature in a position of the control disc that is approached from opposite sides is not guaranteed. Moreover, there is the risk that the cartridge will become leaky when the sealing elements wear out and harden.